Knotted wrack

On October 5th, 2015, our class went to Town Landing. The air was surprisingly warm for the beginning of October and the air was fairly mild. The wind was light with occasional gusts that chilled the air. The sky was bright blue but littered with altocumulus clouds. Closer to the docks the smell of fish was very ripe, almost to an eye-watering point; farther to the right, where we were positioned, the smell was not as strong, it just smelled like ocean: strong, salty, and almost rusty.
Our quadrat was placed on the shore on a muddy, sandy piece of land. A few days before we had record amounts of rain from a hurricane from just off the coast. When standing from the shore and looking at the quadrat, there was a large mass or rocks to the left. Directly to the front and to the left there was a small rock covered in some Ascophyllum Nodosum, or knotted wrack, and some other seaweed. Our quadrat was placed with the top right corner on a rock with the knotted wrack directly in the middle. There were no other species, native or invasive, that interfered or even came close to the knotted wrack. The only thing noticeable about it was the knotted wrack was laying across a rock and the edges were on top of some bladder wrack. After speaking with some other groups they said they saw the green crab taking cover in the knotted wrack. Though I personally did not witness it, the fact is no surprise because the knotted wrack is a common home for up to one hundred animal species. The crab was buried deep within the alga, something our group saw from from the green crab but in different plants.

Supporting Evidence

The knotted wrack has an axial growth pattern. In other words the branches are grown randomly off of the single stem. Though less visible in this image, the cross section was flattened. Though easily confused with the bladder wrack you can tell it is not because there is no vein or midrib that runs down the middle.

From this image you can see the rubbery texture of the alga and the long branches. On this individual plant, the branches grew up to 50 cm long.

The knotted wrack is olive and green-brown-yellow in color. The air bladders are egg shaped found randomly on the branches.

Species Observation: Species Looked For

Did you find it?:

I think I found it

Scientific name:

Ascophyllum nodosum

Common name:

Knotted wrack

Is it alive?:

Some dead & some alive

Count of individuals:

1-10

Coverage:

Between 1/4 and 1/2

Reproduction:

How big is it?:

Greater than 10 cm

Is it male or female?:

Can't tell

Sampling method:

Quadrat (user-placement)

Time search

Place Studied

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Comments

Great observation! From the wonderful field notes to the great photos and descriptions your observation really has it all. I especially liked your field notes (altocumulus clouds - nice!) they really did a great job describing your site conditions and what your peers were finding versus what you found.

Great written evidence too - you did a great job ruling out alternative species and describing different aspects of your specimen. Your photos are clear and really beautiful to look at. You did a nice job capturing how this algae looks on the shoreline with its crazy olive color.